1. Field of the Invention
The present invention relates to an active light sensitive or radiation sensitive resin composition that is suitably used for a production process of VLSIs and high-capacity microchips, a fabrication process of molds for nanoimprint, an ultramicrolithography process applicable for a production process of high-density information recording media, and other photofabrication processes, an active light sensitive or radiation sensitive film, a mask blank provided with the active light sensitive or radiation sensitive film, a pattern forming method, a method for manufacturing an electronic device, an electronic device, and a novel compound. More specifically, the present invention relates to an active light sensitive or radiation sensitive resin composition that can be suitably used for microfabrication of semiconductor elements using an electron beam, X-rays, or EUV light, an active light sensitive or radiation sensitive film, a mask blank provided with the active light sensitive or radiation sensitive film, a pattern forming method, a method for manufacturing an electronic device, an electronic device, and a novel compound.
2. Description of the Related Art
In the microfabrication using a resist composition, ultra fine patterns are required to be formed since integrated circuits are increasingly highly integrated. Consequently, exposure wavelengths also tend to be shortened from g-line and i-line to a KrF laser and an ArF laser, and, in recent years, lithography techniques that use an electron beam, X-rays, or EUV light instead of excimer laser light are under development.
However, from the viewpoint of total performance as a resist, it is extremely difficult to find a suitable combination of a resin, a photoacid generator, a basic compound, an additive, and a solvent, used, and, in particular, in view of recent demand for forming an ultra fine (for example, a line width of 50 nm or less) pattern with high performance, the current situation cannot yet be said to be sufficient.
In electron beam (EB) lithography, it is known that the influence of electron scattering, that is, the influence of forward scattering in a resist film is diminished by increasing an accelerating voltage of an EB. Consequently, in recent years, the accelerating voltage of the EB has tended to increase. However, if the accelerating voltage of the EB is increased, while the influence of forward scattering is diminished, the influence of the scattering of electrons reflected in a resist substrate, that is, the influence of backward scattering is increased. The influence of backward scattering is particularly great when an isolated line pattern having a large exposure area is formed. Accordingly, for example, if the accelerating voltage of the EB is increased, resolution of the isolated line pattern is likely to deteriorate.
Particularly, in a case of forming patterns in photomask blanks used for semiconductor exposure, the lower layer of a resist film includes a light shielding film that contains heavy atoms such as chromium, molybdenum, and tantalum. In this case, the influence of backward scattering caused by reflection from the lower layer of a resist is more marked compared to a case of applying a resist onto a silicon wafer. Consequently, in a case where the isolated line pattern is formed on the photomask blanks, there is a possibility that the pattern will be easily influenced particularly by the backward scattering and that the resolution will deteriorate. On the other hand, in EUV (Extreme Ultra Violet) lithography, due to the surface topology of a reflecting mirror configuring the optical system of an exposure device or flare light generated by a phase difference, and unintended light (Out of Band light: OoB light) of a wavelength different from EUV light, which is generated since the reflecting mirror shows a certain degree of reflection characteristics for even light of a wavelength different from the exposure wavelength (typically, 13.5 nm) of the EUV light, decrease in resolution is likely to be caused.
With miniaturization of a pattern to be formed, a problem that a pattern collapses is newly generated, and thus, to prevent this problem, thinning of a resist film also has been studied. However, due to the influence of swelling of a resist film at the time of development, elimination of the pattern collapse is not sufficient. In contrast, it is reported that, in a case where N-methylol melamine, N-methylol glycoluril, or the like is used as a cross-linking agent, cross-linking is formed while the hydroxyl group in the resist film is eliminated (SPIE Vol. 1672 (1992) 157 and SPIE Vol. 3049 (1997) 974). These cross-linking agents are discussed in JP1989-293339A (JP-H01-293339A), JP1994-301200A (JP-H06-301200A), and the like, and by using these cross-linking agents, the effect in which resolution is improved to some extent is obtained, but, in a resist film thinned for forming a fine pattern, it is not possible to obtain satisfactory results.
Microfabrication using a resist composition is not only directly used for producing integrated circuits but also has been applied for fabricating a so-called mold structure for imprint in recent years (for example, refer to JP2008-268935A, JP2002-6500A, and SPIE Vol. 1672 (1992) 157). Accordingly, even in a case where an ultra fine (for example, a line width of 50 nm or less) pattern is formed by using X-rays, soft X-rays, or an electron beam as an exposure light source, it is important to satisfy high resolution and resist performance such as roughness characteristics at the same time, and thus, there is a problem that needs to be solved.